Effect of Grassland Grazing Systems on Microbial Communities.

Effect of grassland grazing systems on microbial communities

T.L. Carter^1,2, Abbie Lasster¹, Lydia Zeglin³, and C.W. Rice¹

¹Department of Agronomy, Kansas State University, Manhattan, Kansas 66506 USA

²NSF IGERT Graduate Student in Biorefining, Kansas State University, Manhattan, Kansas 66506 USA

³Department of Biology, Kansas State University, Manhattan, Kansas 66506 USA

Climate change is expected to significantly alter precipitation patterns leading to extended drought. Drought can lead to reduced microbial activity and can weaken the interaction between plants and microbial communities. Native grasslands occupy about a quarter of earth’s land surface and are used for domesticated animal production. Grassland management, including burning and cattle grazing, can also affect soil microbial communities. The interaction of climate change and grazing on the soil microbial communities is needed to determine the resilience of grasslands. The objective of this study was to understand the relationship between grassland grazing systems, drought and microbial communities. Soil samples were collected from two burning regimes within Konza Prairie Biological Station in eastern Kansas, USA. The first treatment was annually burned grazed by cattle. The other treatment was burned on a 3 year rotation and grazed annually. The 3 year burn had fields burned in 2013 and 2014. Soil samples were taken in June, July, and August of 2015. Phospholipid fatty acid analysis was conducted to compare differences within the microbial community composition. In June, the gram positive bacteria comprised approximately 45% of the microbial community, followed by gram negative bacteria at 27%, fungi at 14% and actinomycetes at 13%. In June there was no significant difference between burn management. In the annually burned treatment, we observed a decrease in the gram negative and gram positive bacteria and an increase in fungi from June to July. This change may be due to plant growth and changes in seasonal weather.